Compositions containing chlorinated isocyanurates and methods for stabilizing and tabletting the same



United States Patent ce 3,325,411 QOMlPOSITIQNS CONTAINING CHLORHNATED ISOCYANURATES AND METHODS FOR STA- BILIZING AND TAELETTHNG THE SAME Frank N. Stepanek, In, 116 Goodrich Ave, Syracuse, FLY. 13216 No Drawingo Filed June 2, 1964, Ser. No. 372,107 15 Claims. (Cl. 252-99) This invention relates to chlorinated isocyanurates generally and specifically to compositions containing potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid and methods for stabilizing and tabletting the same and is a continuation in part of my prior co-pending United States patent applications Ser. No. 311,638, filed in the United States Patent Office on Sept. 26, 1963, now abancloned, and Ser. No. 360,727, filed in the United States Patent Ofiice on Apr. 17, 1964.

In my co-pending application 360,727, I disclose and claim compositions containing isocyanurates comprising broadly a variety of chlorinated isocyanurates formulated with one or more stabilizing agents selected from a group of acids consisting of sodium mono phosphate, sodium acid pyro phosphate and sodium bisulfate and a group of carbonates consisting of sodium bicarbonate, sodium sesqui carbonate, and sodium carbonate.

In addition, in my aforesaid application, Serial No. 360,727, I disclose and claim a method for tabletting certain bleaching agents including the chlorinated isocyanurates, sodium perborate and sodium mono persulfate each of which exhibits the quality of binding in the die cavity. My method disclosed in this application comprises broadly the introduction of quantities of a wetting agent such as one of the sulfonated dodecylbenzenes and the alkyl sulfonates, which greatly reduce the pressure required to produce an acceptable tablet and prevent the binding of the bleaching agent in the die cavity.

My present invention relates broadly to both the stabilization of chlorinated isocyanurates by formulation with boric acid and methods for the high speed tabletting of the same without binding in the die cavity by combined use of boric acid and the preparation of the chosen chlorinated isocyanurate in a particular physical form and the classification of particles of the same between specific mesh sizes.

It is desirable to provide either or both a tablet or a granular bleach containing an extremely large percentage of a chlorinated isocyanurate in a stable form. Specifically, it is desirable to produce a tablet containing 90% or more trichloroisocyanuric acid, which is the least stable of the chlorinated isocyanurates, wherein approximately 92% of the available chlorine :remains after 12 weeks. This standard is based upon equaling or surpassing the available chlorine level of 5.25% sodium hypochlorite solution under normal storage conditions wherein after weeks approximately 8% of the available chlorine is lost. Such a hypochlorite solution is commercially available today.

It is desirable to provide the chlorinated isocyanurate in the form of a tablet to eliminate the necessity of measuring and to facilitate storage, handling, and the like. However, the chlorinated isocyanurates, as well as some other bleaching agents such as sodium perborate and sodium mono persulfate which for this purpose may be considered as equivalents, exhibit a quality of binding in the die cavity and sticking to the punch faces. Moreover, the said chlorinated isocyanurates have extremely poor flow characteristics in their normally occurring physical state rendering them unusable for high speed tabletting machinery. The final tablet product must be firm, attractive and hard enough to package, store, ship and 3,325,4l i Patented June 13, 1967 otherwise handle. Furthermore, the table must be subject to controlled breakup in water by relatively minor changes in formulation, thus permitting either a very rapid breakup in cold water or a very slow breakup in Warm Water. Of course, in order to accomplish these desideratum, the formulation could include only those reagents compatible with the chlorinated isocyanurates and which would not adversely afiect their stability. Lastly, but by no means of least importance, the cost of the constituents of the tablet must be competitive and the cost of production and equipment held to a minimum.

Therefore, it is among the objects and advantages of my invention to provide compositions containing chlorinated isocyanurates which are extremely stable against the loss of available chlorine over a relatively long period of time sufficient to equal or surpass the available chlorine level in commercially available and popular sodium hypochlorite solutions.

Another object of my invention is to provide compositions containing chlorinated isocyanurates which are readily soluble either in the tablet or the granular form.

A further object of my invention is to provide methods for tabletting chlorinated isocyanurates with relatively low tabletting pressures without 'binding in the die cavity or sticking to the punch face yet which produces a tablet which is stable, tough and attractive.

Yet another object of my invention is to provide methods for treating the chlorinated isocyanurates to render them subject to rapid tabletting in existing high speed machinery.

Still a further object of my invention is to provide compositions containing chlorinated isocyanurates which may be die-pressed into an extremely hard, cohesive, stable tablet the solubility characteristics of which may be easily controlled.

Yet still another object of my invention is to provide a variety of compositions containing chlorinated isocyanurates in either the tablet or granular form which may be employed as home bleaches, sanitizers, bleaching disinfectant agents for institutional use such as hospitals, laboratories, restaurants and the like, disinfectants for tableware, commercial laundry bleaches, swimming pool disinfectants and as a wide variety of other industrial and domestic bleaching, sanitizing and disinfecting agents.

Another object of my invention is to provide compositions containing chlorinated isocyanurates in the granular form which have extremely high flow characteristics adaptable to high speed tabletting machinery.

Still another object of my invention is to provide com positions containing chlorinated isocyanurates in either the tablet or granular form wherein the cost of material other than the chlorinated isocyanurate is relatively inexpensive.

Yet still another objeot of my invention is to provide compositions containing chlorinated isocyanurates formulated with boric acid as a stabilizing agent.

Yet still another object of my invention is to provide compositions containing chlorinated isocyanurates in the tablet form and methods for producing the same in which boric acid is employed to enhance compaction of the chlorinated isocyanurate without binding in the die cavity or sticking to the punch face.

These objects and advantages as well as other objects and advantages may be achieved by my compositions and methods hereinafter set forth.

Presently available synthesized chlorinated isocyanurates occur in extremely fine crystalline or granular particles. These particles exhibit poor flow characteristics tending to agglomerate like flour, and thus are not subject to rapid high speed tabletting. In addition, such finely divided powder does not permit the rapid escape of entrapped air through its mass as it is compacted, thereby increasing the time for tabletting.

Therefore, in order to render the chlorinated isocyanurates physically subject to rapid tabletting in high speed machinery, the initially synthesized finely divided crystals are dried until they contain approximately 1% water or less. The dried crystals are then compacted into thin sheets by rollers, for instance a Fitzpatrick compactor, under pressures ranging from 20,000 to 120,000 pounds per square inch. The most desirable range for my purposes is 60,000 to 90,000 pounds per square inch. It is also desirable to dissipate heat from the rollers during the compacting process in order to maintain the temperature of the crystals at about 50 C. The compacted sheets of crystals are then run through a mill or grinder for reduction to a usably sized particle. The mill or grinder discharge is classified to select granules between to +200 mesh with oversized and undersized particles recycled through the compacting process. While the aforementioned mesh tolerances for classification of materials are acceptable for my process, material classified within the range of -60 to +140 mesh are more desirable.

Boric acid crystals are classified to 200 mesh or less. The boric acid crystals and the chlorinated isocyanurates are then formulated and dry mixed for a period of 15 to minutes. The final tablet product contains approximately 97% or less of the chlorinated isocyanurate and 3% to 15% boric acid by weight. Other ingredients may also be added to enhance the breakup of tablets, control pH or function as fillers. For instance, sodium sulfate is a common filler whereas certain phosphates can be added to increase the pH and enhance the solubility of the chlorinated isocyanurate. Alkali metal salts could also be substituted for this purpose. Corn starch can be added to assist the breakup of the tablet. In addition, olfactory agents, optical brighteners and dyes can be added.

The blended material is fed into a high speed tablet press. The mixture flows freely and permits an even and constant flow through feed devices into the die cavity. My formula can be pressed at a rate of 1 to 60 tablets per minute based upon a single punch die machine without binding in the die cavity, sticking to the punch face, laminating or breaking on the ejection stroke. The pressure of the die must be at least 3 tons per square inch and it may be as great as 40 tons per square inch. The best results are obtained at approximately 15 tons per square inch. The tablet thus produced is ready for packaging.

The boric acid functions to stabilize the chlorinated isocyanurate whether it is in the granular form or tablet form. In addition, the boric acid functions as a lubricant to prevent the chlorinated isocyanurate from sticking to the punch face or binding in the die cavity. While boric acid is a known lubricant, it has heretofore been unknown that the use of boric acid of approximately 200 mesh or less in combination with a chlorinated isocyanurate which has been compacted into sheets, milled or ground and classified between -20 to- +240 mesh is subject to high speed tabletting. However, when tabletting, the chlorinated isocyanurate should comprise 97% or less by Weight of the final product and the boric acid comprise 3 to 15% by weight. If the chlorinated isocyanurate is not in the specified physical form, excessively large percentages of boric acid are required to obtain the necessary lubricating characteristics. This produces a formula having relatively large percentages of fine particles which cannot be tabletted without lamination.

In Schedule A annexed hereto, the relative loss of available chlorine over varying periods of time are compared for two characteristic formulas employing my compositions and methods against formulas disclosed by others. An examination of this table discloses that my Formula Number 1 loses no available chlorine in the tablet form during the first 10 days. After 10 to 12 weeks, tablets of Formula Number 1 stored in the open lose but 1% of available chlorine whereas tablets in closed storage lose by 0.8% available chlorine and ground tablets or granular formulas of the Number 1 variety lose but 0.6%. Similar results are obtained by my formula Number 2 in which even greater quantities of trichloroisocyanuric acid are employed with lesser quantities of boric acid. These results compare favorably with liquid sodium hypo chlorite at 5.25% which loses 8% or 8 times as much available chlorine as the greatest loss in my formulas.

Other examples of my formula may be derived by substituting one of the other aforementioned chlorinated isocyanurates for the trichloroisocyanuric acid in Formulas l and 2 in Schedule A.

While in tablet applications there must be at least approximately 3% by weight boric acid, thereby limiting the chlorinated isocyanurate to approximately no more than 97% by Weight, this limitation does not apply to granular compositions wherein sticking to the punch or binding in the die cavity is not encountered. In a granular composition, only the stability of the chlorinated isocyanurate is in issue. I have found that stability can be effected by as little as approximately 1% by weight of boric acid to as much as appriximately 99% by weight chlorinated isocyanurate.

SCHED ULE A Form Percent Available Chlorine Loss After 10-12 Weeks Percent Available Chlorine Loss During 1st 10 days Ground Tablets or Granular,

percent Open Storage Closed Storage Tablets, Tablets, percent percent Applicant Formula Number 1 Trichloroisocyanurate Acid, 90.5%. Powdered Boric Acid, 3.2%. Corn Starch, 6.3%. Formula Number 2.

Trichloroisocyanurate Acid, 93.7%. Powdered Boric Acid, 1.9%. Corn Starch, 4.4%. Competitive Formula Number 1 Trichloroisocyanurate Acid, 8.3%. Sodium Aryl Akyl Sulfonate, 2.2%. Sodium Sulfate, 54.5%. Sodium Tripoly Phosphate, 35%. Competitive Formula Number 2 Trichloroisocyanurate Acid, 8.3%. Sodium Sulfate, 44.5%. Sodium Metasilicate, 10%. Sodium Tripoly Phosphate, 35%. Sodium Aryl Akyl Sulionate, 2.2%. Liquid Sodium Hypochlorite, 5.25%

Water, 94.75%. Sodium Hypochlorite, 5.25%.

Tablet 0 6 Granular.

Liquid 4 1 Liquid.

I claim:

l. A composition of matter consisting essentially of:

(a) at least one bleaching agent selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid, and

(b) boric acid in an amount of not less than approxi mately 1% of the combined weight of the selected bleaching agent and the boric acid.

2. A composition of matter consisting essentially of:

(a) a compacted mass in the form of a tablet having at least one bleaching agent selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid,

(b) boric acid in an amount of not less than approximately 3% of the combined weight of the selected bleaching agent and the boric acid and not more than approximately by Weight of the entire tablet.

3. A composition of matter consisting essentially of:

(a) a compacted mass in the form of a tablet having at least on bleaching agent selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dischloroisocyanuric acid and trichloroisocyanuric acid,

(b) boric acid in an amount of not less than approximately 3% of the combined weight of the selected bleaching agent and the boric acid and not more than approximately 15% by weight of the entire tablet,

(c) the selected bleaching agent having been preclassified to between to +240 mesh and the boric acid having been pre-classified to no larger than 200 mesh before being mixed with each other and thereafter compacted into the form of a tablet.

4. A composition of matter consisting essentially of:

(a) the composition as set forth in claim 2 in which,

(b) the selected bleaching agent contains no more than approximately 1% water.

5. A composition of matter consisting essentially of:

(a) the composition as set forth in claim 3 in which,

(b) the selected bleaching agent contains no more than approximately 1% water.

6. A method for producing tablets containing stabilized chlorinated isocyanurates comprising:

(a) dry mixing at least one bleaching agent selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid with boric acid in amounts of not less than approximately 3% boric acid, and not more than approximately 15 by weight of the entire tablet to define a tablet press charging mixture, the boric acid being substantially homogeneously distributed throughout the mixture,

(b) charging the said mixture into a tablet press,

(c) exerting pressure on the mixture in the press sufficient to form a cohesive, compacted mass, and

(d) removing the cohesive, compacted mass from the tablet press.

7. A method for producing tablets containing stabilized chlorinated isocyanurates comprising:

lized chlorinated isocyanurates comprising:

(a) the procedure in accordance with claim 7 in which,

(b) the classified bleaching agent contains no more than approximately 1% water. 9. A method for producing tablets containing stabilized chlorinated isocyanurates comprising,

(a) compacting particles of at least one bleaching agent selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid having no more than approximately 1% water into a sheet,

(b) crushing the sheet of bleaching agent to particles,

(c) classifying the particles of bleaching agent to between -20 to +240 mesh,

(d) dry mixing the classified particles of bleaching agent with boric acid classified to no larger than approximately 200 mesh in an amount of no less than approximately 3% boric acid by weight of the combined boric acid and selected bleaching agent and not more than approximately 15% by weight of the entire tablet to define a tablet press charging mixture, the boric acid being substantially homogeneously distributed throughout the mixture,

(e) charging the said mixture into a tablet press,

(f) exerting pressure on the mixture in the press sufficient to form a cohesive compacted mass and,

(g) removing the cohesive, compacted mass from the tablet press.

10. A method for stabilizing certain chlorinated isocyanurates comprising:

(a) intimately mixing at least one chlorinated isocyanurate selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid with boric acid in amounts of not less than 1% nor more than approximately 15% boric acid by weight of the combined boric acid and selected bleaching agent, the boric acid being substantially homogeneously distributed throughout the selected chlorinated isocyanurate.

11. A method for stabilizing certain chlorinated isocyanurates comprising,

(a) mixing at least one chlorinated isocyanurate selected from the group consisting of potassium dichloroisocyanurate, sodium dichloroisocyanurate, dichloroisocyanuric acid and trichloroisocyanuric acid with a quantity of boric acid sufiicient to stabilize the selected chlorinated isocyanurate against undesired loss of available chlorine, the boric acid being substantially homogeneously distributed throughout the selected chlorinated isocyanurate.

112. A method for stabilizing certain chlorinated isocyanurates comprising,

anurates comprising:

(a) the method in accordance with claim 11 in which,

(b) the selected chlorinated isocyanurate contains no more than approximely 1% water prior to mixing thereof with the boric acid.

15. A method for stabilizing certain chlorinated isocyanurates comprising,

(a) mixing at least one chlorinated isocyanurate selected from the group consisting of potassium di- 7 8 chloroisocyanurate, sodium dichloroisocyanurate, di- References Cited chloroisocyanurlc acid and trlchlorolsocyanunc acid UNITED STATES PATENTS with boric acid, (b) the selected isocyanurate and boric acid being 3,042,622 7/1962 Klrschenbauer 25%99 sufficiently finely powdered and being sufficiently 5 3120'378 2/1964 Lee et 252*99X thoroughly mixed and the boric acid appearing in a t quantity sufficient to stabilize the selected chlorinated LEON ROSDOL Primary Exftmmer' isocyanurate from undesired loss of available JULIUS GREENWALD, Exwmmerchlorine. M. WEINBLATT, Assistant Examiner. 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF: (A) AT LEAST ONE BLEACHING AGENT SELECTED FROM THE GROUP CONSISTING OF POTASSIUM DICHLOROISOCYANURATE, SODIUM DICHLOROISOCYANURATE, DICHLOROISOCYANURIC ACID AND TRICHLOROISOCYANURIC ACID, AND (B) BORIC ACID IN AN AMOUNT OF NOT LESS THAN APPROXIMATELY 1% OF THE COMBINED WEIGHT OF THE SELECTED BLEACHING AGENT AND THE BORIC ACID. 